block 2 quiz/exam Flashcards
1
Q
Primordial
A
The goal is to stop/reduce immergence of disease (Tabacco tax laws)
2
Q
Primary
A
Control risks via vaccines & safe water etc
3
Q
Secondary
A
Early detection (screening like mammograms, BP/BS testing)
4
Q
Tertiary
A
Reduce complications associated with disease (rehab and better treatment)
5
Q
Equation for infectivity
A
Infected
/
Exposed
6
Q
Equation for virulence
A
Ill
/
Infected
7
Q
Equation of pathogenicity
A
Ill
/
Exposed
8
Q
Describe categorical/qualitative nominal
A
Things that can’t be ordered like gender/blood group/married status
9
Q
Describe categorical/qualitative ORDINAL
A
Things that can be in ordered categories (smoker/non-smoker/ex-smoker, stage of disease, & pain scale)
10
Q
Describe numerical/quantitative DISCRETE
A
Numerical values you can count i.e number of days sick from work
11
Q
Describe numerical/quantitative CONTINUOUS
A
Numerical ranges Height, weight, age etc
12
Q
Equation for case fatality rate
A
of deaths due to disease
/
# of disease cases
13
Q
Equation for 5 yr survival rate
A
patients alive @ the END of 5yrs
/
# patients alive @ START of 5yrs
14
Q
Equation for Relative survival rate
A
Observed # of plp alive with disease
/
expected # survival if they didn’t have disease
15
Q
Sensitivity describes
A
people with disease
16
Q
Specificity describes
A
disease-free people
17
Q
PPV Positive-predictive value
A
People have the disease with a positive test
18
Q
NPV Negative predictive value
A
People that don’t have the disease with a negative test
19
Q
Describe a True positive
A
Has the disease & a positive test (pregnant lady + positive preggo test)
20
Q
Describe a True negative
A
No disease with a negative test (Man with negative preggo test)
21
Q
Describe a false positive
A
No disease with a positive test
(man with a positive preggo test)
22
Q
Describe a false negative
A
Disease with a negative test (pregnant lady with a negative preggo test)
23
Q
Sensitivity equation
A
TP
/
(TP+FN)
24
Q
Equation for specificity
A
TN
/
(FP+TN)
25
Equation for PPV
TP
/
(TP+FP)
26
Equation for NPV
TN
/
(TN+ FN)
27
Equation for accuracy
TP + FP
/
ALL
28
Equation for prevalence
TP +FN
/
ALL
29
Low threshold indicates what?
high sensitivity and FP's (aka low specificity)
30
High threshold indicates what?
high specificity and FN's (aka low sensitivity)
31
Botulism is a ____ category disease
A
32
Brucellosis is a ______ category disease
B
33
Anthrax is a ______ category disease
A
34
Nipah virus is a ______ category disease
C
35
H2N2 is a ______ category disease
C
36
Bubonic plague is a ______ category disease
A
37
Tularemia is a ______ category disease
A
38
Q. fever is a ______ category disease
B
39
SARS is a ______ category disease
C
40
Small pox is a ______ category disease
A
41
Hemin fever is a ______ category disease
A
42
Staphylococcal infections are a ______ category disease
B
43
Hanta virus is a ______ category disease
C
44
Racin toxin is a ______ category disease
B
45
Typhus is a ______ category disease
B
46
Psittaeosis is a ______ category disease
B
47
Study types:
Ecological
Compares people in different places at the same time
A study that assesses links between an exposure and an outcome usually in larger populations (countries etc)
48
Study types:
Cohort study
Study involves a group with common characteristics (exposed vs unexposed) over a period of time
Prospective (looking forward happens before the groups develop an outcome
Retrospective (looking backwards) happens after the exposed group has developed an outcome
49
Study types:
Case control
2 groups (exposed vs control) to find if exposed are associated with an outcome (i.e is a risk factor ass with developing a disease)
50
A group of patients with histologically confirmed cervical cancer (cases) is compared to otherwise similar patients without histologically confirmed cervical cancer (controls) for the presence of human papillomavirus (exposure).
Case control
51
Determining the incidence of cholera deaths in different parts of a city to identify the source of exposure
Ecological study
52
Investigating the number of patients with both coronary heart disease and hypertension in the year 1998
Cross-sectional study
53
Study types:
Cross-sectional
Determines the prevalence of exposure and disease at a specific point in time
54
Individuals with a smoking history of ≥ 1 pack of cigarettes a day (exposed group) are compared to individuals who are nonsmokers to see if there is a difference in the proportion of patients in each group that develop lung cancer (e.g., the outcome) within a specific follow-up period.
Prospective cohort study
55
Individuals with a smoking history of ≥ 1 pack of cigarettes a day (exposed group) 5 years ago are compared to individuals who were nonsmokers 5 years ago to see if there is a difference in the proportion of patients in each group that eventually developed lung cancer (outcome) within a specific follow-up period.
Retrospective cohort study
56
Study types:
Randomized control trial
determine the possible effect of a specific intervention on a given population
57
Study types:
Randomized cluster trial
an experimental study design in which the unit of randomization is a group rather than an individual participant
58
Study types:
Field trials
to determine the effect of disease prevention interventions in individuals who do not already have a disease
59
Study types:
Community trials
similar to field trials, but follow communities rather than individuals
60
observation of children who did and did not receive the Salk vaccine for prevention of poliomyelitis to see whether they developed paralysis or death
Field trial study
61
studying the incidence of myocardial infarction and stroke in communities who implement lifestyle changes to prevent cardiovascular disease compared to communities who do not implement such changes
Community trial study
62
Describe Random error
Definition: an error that occurs due to chance and/or limitations of precision
63
How can random error be limited?
It can be reduced by repeated measurements and averaging over a large number of observations
- Increasing sample
- Assessing statistical significance
64
Describe Systematic error
An error in the study design or the way in which the study is conducted that causes systematic deviation of findings from the true value
65
Selection bias
The individuals in the sample group are not representative of the population from which the sample is drawn because the sampling or the treatment allocation is not random
66
Sampling bias (ascertainment bias)
Occurs when certain individuals are more likely to be selected for a study group, resulting in a nonrandom sample
This can lead to incorrect conclusions being drawn about the relationship between exposures and outcomes.
Limits generalizability
67
Healthy worker effect:
The working population is healthier on average than the general population The working population is healthier on average than the general population
68
Volunteer bias
Individuals who volunteer to participate in a study have different characteristics than the general population.
69
Survival bias (prevalence-incidence bias or Neyman bias)
Happens when the observed subjects have a more or less severe case of disease compared to the standard individual exposed
Note if the people with severe disease die before observation then it means people with milder disease will be observed
&
if people with the milder disease resolves before observation then those with the more severe strain will be reported
70
Survivor bias is most common in which 2 studies
cross-sectional and case control
71
Measurement bias
any systematic error that occurs when measuring the exposure or outcome
72
Observer bias (experimenter-expectancy effect or Pygmalion effect)
The measurement of a variable or classification of subjects is influenced by the researcher's knowledge or expectations.
73
Reporting bias
a distortion of the information from research due to the selective disclosure or suppression of information by the individuals involved in the study
Can involve the study, design, analysis, and/or findings
Results in underreporting or overreporting of exposure or outcome
74
Recall bias
awareness of a health condition by subjects means they might recall more related risk factors associated with their condition (recall a certain exposure)
Common in retrospective studies
75
After claims that the MMR vaccine caused autism became public, parents of children diagnosed with autism were more likely to recall the start of autism being soon after their child was vaccinated, as compared with parents of children who were diagnosed with autism prior to these claims becoming public.
Recall bias
76
Attrition bias
A type of nonresponse bias
Selective loss of participants to follow up
Most commonly seen in prospective studies
Risk that the remaining participants differ systematically from those lost to follow up
77
Lend time bias
A type of bias in which survival time is overestimated because of early diagnosis through screening and does not reflect an actual delay in mortality
This happens when survival times are chosen as an endpoint of screening trials.
78
Lead time is described as
the length of time between the initial detection of disease and the expected outcome (i.e., death or onset of clinical symptoms)
79
Central tendency bias
measures to describe a common, typical value of a data set (e.g., clustering of data at a specific value)
80
Misclassification bias
an error in which research subjects are classified into the wrong exposure or outcome groups, thereby distorting the observed association
81
In a study on risk factors for lifetime cancer diagnosis, participants are asked if they have ever been exposed to radiation but are not asked for further clarification (e.g., what type, how recently, for how long). This leads to an incorrect conclusion about the association between radiation exposure and lifetime cancer diagnosis. Because all participants were asked the same vague question, the frequency of classification errors is similar across exposed and unexposed groups.
Misclassification bias
82
actions that address environmental, socioeconomic, and behavioral risk factors that affect a population as a whole to prevent potential disease or injury.
primordial prevention
83
Programs on food safety and nutrition guidelines
Primordial
84
Campaigns discouraging tobacco and drug use (e.g., smoke-free air laws in public buildings)
primordial
85
Building bicycle and sidewalks to promote physical activity
primordial
86
actions targeted at preventing specific diseases from occurring to decrease the incidence and, subsequently, the prevalence of those diseases
Primary
87
Immunization
Primary
88
Lifestyle modification (e.g., smoking cessation to reduce lung cancer risk, exercise to reduce the risk of heart disease, dental care to reduce the risk of tooth loss)
Primary
89
Fortification of salt with iodine to prevent iodine deficiency
Fluoridation of toothpaste, water, and salt to reduce the risk of dental conditions
primary
90
Fortification of food with folic acid to reduce the prevalence of neural tube defects
primary
91
Health legislation (e.g., seat belt laws, food safety standards, traffic laws)
primary
92
Ocular prophylaxis for all newborns to prevent neonatal gonococcal conjunctivitis
primary
93
actions targeted at early detection of disease in asymptomatic patients (or while the symptoms of the condition are still mild) to promote early intervention
Secondary
94
actions taken to optimize care of patients with an existing disease to improve well-being and prevent complications
tertiary
95
Adjuvant therapy (e.g., tamoxifen in breast cancer) to reduce risk of cancer recurrence
tertiary
96
Blood pressure management (e.g., antihypertensives) to decrease risk of a cardiovascular event
PRIMARY
97
Diabetes management (e.g., antidiabetic medication
tertiary
98
HbA1c monitoring) to decrease risk of chronic kidney disease and/or cardiovascular events
tertiary
99
Measures to prevent restenosis following myocardial infarction (e.g., low-dose aspirin)
tertiary
100
Categorical variable (nominal variable):
variables that have a finite number of categories that may not have an intrinsic logical order
101
Continuous variable (nondiscrete variable):
variables that can assume any real number value
102
Discrete variable
Discrete variable: variables that can only assume whole number values
103
Variable scales
Definition:
types of measurement scales (categorized as categorical scales and metric scales
104
Categorical scale (qualitative)
The distance (interval) between two categories is undefined.
Includes the nominal scale and ordinal scale
105
Metric scale (quantitative)
The distance between two categories is defined and the data can be ranked .
Includes the interval scale and ratio scale
106
a researcher examined the rates of lung cancer in different countries and the levels of cigarette consumption in those countries. The study compares the frequency of lung cancer and the frequency of cigarette use across the populations of different countries. This study could be used to investigate whether smoking rates impact the occurrence of lung cancer at a population level.
What is the study type and it's limitation
Ecological study
&
The results of this study cannot be directly applied to individuals, as they only apply to population-level data and cannot account for individual differences in risk factors. (Ecological fallacy)
107
A study between the link smoking and lung cancer. We select a group of 10,000 people aged 50-75, who are lifelong smokers, and track them for 10 years. We compare this group against another 10,000 people aged 50-75 who have never smoked. We then observe the incidence of lung cancer in both groups over the 10-year period and compare the results.
What is the study?
Prospective Cohort study
108
Describe what an ecological study is?
A study that looks at how often a disease occurs and how often a certain risk factor is present in different groups of people (population)
109
Describe an ecological fallacy
Applying the results of an ecological study to the individual members within that population.
The results of an ecological study are only relevant to the group/pop as a whole
110
Describe a cohort study
A study that compares two groups. One with a risk factor/exposure & one without (control) to see i the risk factor/exposure is linked to the development of a disease
It can be forward looking (prospective) aka follows people over time
Or
Can be backward-looking (retrospective) aka looks at medical records & history
111
we want to investigate the link between a certain chemical exposure and cancer of the bladder. We select a group of 100 people who have been diagnosed with bladder cancer and 100 people who do not have the disease. We then look back at their medical records to see if they had any prior exposure to the chemical in question. By comparing the exposure rates of both groups, we can determine if there is an association or correlation between the exposure and the development of the disease. The study asks the question of what happened, trying to find out if prior exposure to the chemical led to the development of the disease
What is the appropriate study type to use?
Case-control study
112
Describe a case-control study
A retrospective study looks t groups of people and compares people who have a disease vs people that don't to determine if there is a risk
uses odds ratio
113
describe the odds ratio
It looks at whether the odds of being exposed to a risk factor are different between the groups and if the contributes to disease
ex.Patients with COPD had higher odds of a
smoking history than those without COPD
114
Describe a cross-sectional study
A study that looks at the frequency of a disease and the frequency of risk-related factors in the population at a present time
"find out what's happening now in terms of prevalence and risk factors"
114
we want to investigate the prevalence of obesity and the frequency of certain risk factors for obesity, such as lack of exercise and unhealthy eating habits. We survey 1000 randomly selected individuals and collect data on their height, weight, exercise habits, and eating habits. We can then use this data to determine the frequency of obesity and the frequency of the risk factors in our population sample
What is the appropriate study type?
cross-sectional
115
a cross-sectional study specifically measures what variable?
disease prevalence
116
a cohort study specifically measures what variable?
Disease incidence
117
we want to investigate whether a particular drug is effective in treating a particular type of cancer. We select ten patients who have been diagnosed with the same type of cancer and have been treated with the drug. We then describe the experiences of each patient, including their diagnosis, treatment, and outcome. By looking at the similarities and differences between these cases, we can learn more about the effectiveness of the drug for this particular type of cancer.
What study type does this describe?
Case-series
118
Describe case series
A study that looks at patients with similar experiences (diagnosis, treatment, or outcome) and analyses their outcomes
119
, if researchers are studying the relationship between a particular illness and exposure to a certain chemical, they may ask people who have the illness to recall their previous exposure to the chemical. However, if the people being asked already know that the chemical is being studied for its link to the illness, they may think more about whether they were exposed to it than they would have if they didn't know this. This affects the reliability of the study results because it cannot be sure whether the reported exposure is accurate or not.
This describes what type of bias?
Recall bias
120
Describe the recall bias
When people know they have a disorder, they may recall things differently than those that don't know when asked in a study
121
Describe selection bias
not randomly selecting individuals for a sample or allocating treatment groups, it doesn't represent the actual population
122
Describe Berkson bias
aka the bedside bias. Researcher choose cases/controls from the hospital who tend to be less healthy and have different exposures than the actual population
123
Describe the attrition bias
Participants lost before follow up have different prognoses to those who complete the study
124
if a study is conducted on a particular population, but only a certain group of people are surveyed, the information collected may be systematically distorted because the views of the people who were not surveyed are not reflected in the results. Similarly, if information is collected using biased questions or questions that only focus on certain aspects of a topic, this can also lead to systematic distortion
this describes what type of bias?
Measurement bias
125
Describe measurement bias
Information is gathered in a way that is inaccurate or biased it can be due to a number of factors including the Hawthorne effect
126
Describe the Hawthorne effect
participants
change behavior upon
awareness of being observed
127
Describe the lead-time bias
when a disease is detected early, it is often thought that this leads to a better chance of survival even though the course of the disease hasn't changed
128
Describe the features of the figure
Normal distribution:
The best measure of central tendency where mean=median=mode are all equal
129
Describe the figure
Negative skew:
Longer tail to the left
mean
130
Describe the figure
Positive skew:
Longer right tail
mode>median>mean
131
Describe the following figure
Bimodal:
Suggests two different populations
132
Describe the mean
It's MOST affected by outliers
Sum of all values
/
total number of values
133
Describe median
The middle value of an odd set and the average between the two middle numbers of an even set
134
Describe the mode
The most common value in the set
It's the LEAST affected by outliers
135
Calculate the median survival times for line A & B
A 3
B 8
136
A standard urine test used to detect cocaine has a sensitivity of 97%, a specificity of 94%, a positive predictive value of 90%, and a negative predictive value of 95%. Recent data suggest that the use of cocaine in all age groups has declined since the screening test properties were determined. A decline in cocaine usage will most likely have which of the following impacts on the results of this screening test?
Increase the negative predictive value
137
A test is used in 50 people with disease and 50 people without. These are the results:
fill in the table
138
Describe the addition rule
If two events (A&B) can't happen at the same time i.e rolling a 3 & 5 on dice, then the probability of them happening is equal to the sum of their INDIVIDUAL probabilities
ex. roll a 2 & 6 (1/6 chance for either) 1/6+1/6 = 2/6 or 1/3
139
Describe the multiplication rule
If 2 events (A&B) are independent of each other (one occurring doesn't effect the other) then the probability of both happening is equal to the product of their original probabilities
ex. rolling a 6 (1/6) & flipping heads on a coin (1/2); 1/6*1/2 = 1/12
140
precision
Test precision in epidemiology refers to how accurately a diagnostic test or screening tool can detect the presence or absence of a specific disease or condition. In simpler terms, it is a measure of how well the test can correctly identify whether someone has a particular disease or not. A highly precise test will have a low rate of false positives (incorrectly classifying someone as having the disease when they do not) and false negatives (failing to identify someone as having the disease when they actually do)
141
Accuracy
In epidemiology, test accuracy refers to how well a medical test can correctly identify or rule out a particular condition or disease
test with high accuracy will have a low number of false positives (healthy people wrongly identified as having the condition) and false negatives (sick people wrongly identified as not having the condition).
142
Validity
it measures whether a test can correctly identify people with a disease or condition and exclude people who do not have the disease or condition. A valid test is important in epidemiology because if a test is not reliable, the results and conclusions that are based on that test may be misleading or inaccurate. To determine the validity of a test, researchers compare the results of the test with a gold standard diagnostic tool to assess its accuracy
